libexpat through 2.10.0 Out-of-Bounds Read via unknown_toUtf8 and unknown_toUtf16
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Not reported
Do first: Apply the patch listed under Evidence.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 23/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
libexpat, an XML parsing library, is affected by an out-of-bounds read flaw in its handling of application-registered unknown encodings. A remote attacker, without logging in, can supply a document ending in a truncated multibyte sequence to leak adjacent memory or crash the application.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
libexpat through 2.10.0 contains an out-of-bounds read vulnerability in unknown_toUtf8() and unknown_toUtf16() in xmltok.c when handling application-registered unknown encodings. Attackers can supply a document ending in a truncated multibyte sequence so the convert callback reads past the parse buffer, leaking adjacent memory or crashing applications.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity6.3/10CVSS 6.3
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 28 if advisories confirm default setups are exposed
What to do
Apply the patch listed under Evidence.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- libexpat libexpat
through 2.10.0
Evidence 4
- Patch
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-124317
Is CVE-2026-124317 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-124317?
libexpat: through 2.10.0.Source: cve.now feed data